From mboxrd@z Thu Jan 1 00:00:00 1970 From: Changli Gao Subject: Re: [PATCH] sch_htb: ix the deficit overflows Date: Tue, 1 Dec 2009 10:32:26 +0800 Message-ID: <412e6f7f0911301832o53e479f0x42345065b0b1616f@mail.gmail.com> References: <4B0F8A5D.1040806@gmail.com> <20091128000401.GA3713@ami.dom.local> <412e6f7f0911292026w704a70b8yc3af2c2473e05d34@mail.gmail.com> <20091130111020.GA7114@ff.dom.local> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Jamal Hadi Salim , "David S. Miller" , netdev@vger.kernel.org, Martin Devera To: Jarek Poplawski Return-path: Received: from mail-pw0-f42.google.com ([209.85.160.42]:39304 "EHLO mail-pw0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751017AbZLACcT convert rfc822-to-8bit (ORCPT ); Mon, 30 Nov 2009 21:32:19 -0500 Received: by pwi3 with SMTP id 3so2239593pwi.21 for ; Mon, 30 Nov 2009 18:32:26 -0800 (PST) In-Reply-To: <20091130111020.GA7114@ff.dom.local> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, Nov 30, 2009 at 7:10 PM, Jarek Poplawski wr= ote: > On Mon, Nov 30, 2009 at 12:26:33PM +0800, Changli Gao wrote: > > Users can control this with "r2q" and "quantum", and there is a hint > on quantum size in the user's guide. Yes. But I think most of users will ignore it like me. > >> And >> if we use IMQ to shape traffic, the skb will be defragmented by >> conntrack, and its size will be larger than MTU. > > IMQ is a very nice thing, but it's considered broken as well, so it > can't be the reason for changing HTB. I find IMQ is used by many network equipments Linux based. Why not fix and integrate it into official Linux? > And this patch is very similar, except ->peek()/dequeue(). Additional > lookups are done instead of dequeuing the first found class, which > might be quite long in some cases. If the quantum is set correctly, there isn't difference except of a comparison. In the other case, I think some additional CPU cycles are better than overflow. > > It's not acceptable to me mainly because the real change done by this > patch is different than you describe: preventing an overflow might be > simple. You change the way DRR is implemented here, and even if it's > right, it should be written explicitly and proved with tests results. > This way is used by CBQ. > Anyway, I think you should rather care for the author's acceptance, > because the way it's done doesn't look like accidental and has been > heavily tested btw. (I added Martin to CC.) > > Regards, > Jarek P. > > PS: Btw, this newer version of the patch is broken with spaces. > Thanks. It is why I ask for posting again. --=20 Regards=EF=BC=8C Changli Gao(xiaosuo@gmail.com)